Downhole tools used in the oil and gas industry and, more particularly, to wellbore isolation devices that use solid sealing elements are described herein.
In the drilling, completion, and stimulation of hydrocarbon-producing wells, a variety of downhole tools are used. For example, it is often desirable to seal portions of a wellbore targeted for treatment. For example, during fracturing operations, various fluids and slurries are pumped from the surface into the casing string and forced out into a surrounding subterranean formation, but only certain desired zones of interest should receive the fracturing fluid. It thus becomes necessary to seal the wellbore and thereby provide zonal isolation to target the treatment to the desired zone. Wellbore isolation devices, such as packers, bridge plugs, and fracturing plugs (i.e., “frac” plugs) are designed for these general purposes and are well known in the art of producing hydrocarbons, such as oil and gas. Such wellbore isolation devices may be used in direct contact with the formation face of the wellbore, with a casing string extended and secured within the wellbore, or with a screen or wire mesh.
After the desired downhole operation is complete, the seal formed by the wellbore isolation device must be broken and the tool itself removed from the wellbore. Removing the wellbore isolation device may allow hydrocarbon production operations to commence without being hindered by the presence of the downhole tool. Removing wellbore isolation devices, however, is traditionally accomplished by a complex retrieval operation that involves milling or drilling out a portion of the wellbore isolation device, and subsequently mechanically retrieving its remaining portions. To accomplish this, a tool string having a mill or drill bit attached to its distal end is introduced into the wellbore and conveyed to the wellbore isolation device to mill or drilling out the wellbore isolation device. After drilling out the wellbore isolation device, the remaining portions of the wellbore isolation device may be grasped onto and retrieved back to the surface with the tool string for disposal. As can be appreciated, this retrieval operation can be a costly and time-consuming process.